The following is an excerpt from Sing Like Fish: How Sound Rules Life Under Water by Amorina Kingdon

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Sing Like Fish: How Sound Rules Life Under Water

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One summer day when we were kids, my brother and I threw our toy trucks off the dock into the lake in front of our house. We watched our miniature yellow graders and cement mixers sink 2 meters to the bottom. Then we jumped in after them. We drove the trucks around the lake bed just as we drove them around the dirt pit and throughout our forested acre in rural Ontario, expanding our domain into the aquatic, between hastily gulped breaths at the surface. We graded pebbles in the shallow fish nests, bulldozed the pondweed and milfoil. We used the digger to load silt clods into the dump truck. At one point, we tried to talk to each other and discovered that, underwater, sound didn’t seem to work.

My brother sounded faint and garbled, even when he swam close and screamed a bubble stream. My own voice was loud in my head, but he couldn’t hear me. Inevitably, we spent some time shouting all the bad words we knew with impunity.

I remember the rattle of my cement mixer’s wheels over the algae-furred rocks was perfectly clear but seemed somehow unconnected to the truck in my hands, as though the sound came from nowhere and all around at once. When a motorboat passed, out in the bay, the outboards that made a lusty buzz in the air were higher-pitched underwater, like a mosquito instead of a hornet. And when Mom’s wavering silhouette appeared on the dock, we didn’t hear her at all. We could only see her arms moving, beckoning us to (what we could only guess was) lunch.

Underwater trucks was fun, for a day or two. But my brother and I soon hauled our dripping fleet back to the sandpit. We couldn’t hear what we needed to, or trust what we did. We couldn’t communicate, which is essential to a good game of trucks.

This was when I first paid attention to sound underwater. Most people experience something similar. Dunking our heads in the bathtub to rinse shampoo, or frog-kicking through a swimming pool, we notice sound is faint, distorted, and apparently contains little useful information. We assume it doesn’t work. And where we can’t sense a world, it’s difficult to imagine one exists. For most of human history, our own ears were all we had with which to listen, and human ears are not evolved to work underwater.

In his 1956 film The Silent World, Captain Jacques-Yves Cousteau describes in soothing, French-accented English the undersea adventures of the crew of the ship Calypso. During World War II, Cousteau had co-developed a regulator, which allowed humans to breathe from pressurized tanks while diving. Pairing scuba (originally an acronym for “Self-Contained Underwater Breathing Apparatus”) with underwater videography, Cousteau and his slim, swim-trunk-clad crew, cylinders of air strapped to their backs, swam through coral reefs, among whales, fish, and other creatures, and into the deep. “We have merely skimmed the surface of the ocean,” Cousteau narrates to close the film. “Someday we will go much deeper to new discoveries waiting in the silent world.” The film became widely known, and its trope of the ocean as a silent world has persisted.

Yet through the nineteenth and twentieth centuries, research driven by warfare, commerce, and curiosity gave rise to technologies like hydrophones, special microphones designed to work in water. Humans began to hear the stunning breadth of aquatic sounds we had been missing. We discovered that for many aquatic animals, while other senses—sight, taste, smell, touch—are often diminished in water, sound becomes enhanced.

As it does above the water, sound carries over distance, in darkness, and around objects. But underwater it travels four and a half times faster than in air, and the right sound under the right conditions can cross seas. Sound holds critical information and mediates vital interactions.

We’ve learned that whales make more sounds than we’d ever imagined. Some social whales define their groups with unique dialects: Some who have what is arguably “culture”—and debates rage about what this word means for animals and humans—transmit that culture through their calls and even their songs.

We have confirmed that fish can hear, and learned they make many sounds, even daily choruses. Some fish who must find each other to mate drum their swim bladders with some of the fastest muscles in the animal kingdom.

More recently, we’ve learned how even animals like corals, octopuses, and lobsters, which seem to make few sounds, or have nothing we could call an ear, detect sound beneath the water. Even tiny larvae that must find a hospitable shore, detect the sounds of the coast to find a safe home.

With the help of technology, we’ve found some animals fraternize in frequencies beyond our perception. Gear designed to sense earthquakes picks up fin whales’ low-pitched voices, while dolphins, porpoises, and their toothed-whale brethren peer about the ocean with high-frequency biosonar clicks far above our hearing range, their abilities still unmatched by naval sonar.

We are finding that underwater, sound is the best way to learn about the world, and to communicate, for many animals.

As biologists Hal Whitehead and Luke Rendell write, “The movement of information is the basis of biology. Life happens and creatures evolve because information is transferred.” Underwater, information is often—not always, but often—sent and received most accurately, most quickly, over the greatest distances, with sound.

In short: underwater, sound mediates lives.

This book seeks to explain why sound is so important to animals underwater, how sound behaves differently in water than in air, why we haven’t always listened beneath the waves, what we learn when we do, and what we miss when we don’t.

Excerpted from SING LIKE FISH: How Sound Rules Life Under Water by Amorina Kingdon. Copyright © 2024 by Amorina Kingdon. Published in the United States by Crown, an imprint of the Crown Publishing Group, a division of Penguin Random House LLC, New York. All rights reserved.